Treatment of carbonaceous materials



NOV. 4, 1930. LESSlNG 1,780,830

TREATMENT OF CARBONACEOUS MATERIALS Filed May 23, 1927 2 Sheets-Sheet l ATTORNEYS Nov. 4, 1930. R, LESSING TREATMENT OF CARBONACEOUS MATERIALS Filed May 25, 1927 2 Sheets-Sheet 2 INVENTOR ATTORNEYS Fudfllf' Leasing- BY im; Noah/M4441 Patented Nov. 4, 1930 PATENT OFFICE 7 RUDOLIB LESSING, 01 LONDON, ENGLAND TREATMENT or cmonacaous MATERIALS Application filed Kay 23, 1927, Serial K0. 193,610, and in Great Britain Kay 27, 1928.

or less of ash. The present process renders, commercially possible the separation from coal in bulk of a low ash forming component and a high ash forming component 1n an improved manner. In this process advantage is taken of the difference in specific gravity of those components whereby they can be separated by flotation of the lighter fra ments in an aqueous solution whose speci c gravity lies between the specific gravities of the components.

By the present invention, clean coal having a lower proportion of ash forming ingredients than any'commercially available at present, so far as I am aware, may be produced.

In order to. render the separat on economlcally practicable it is necessary to recover the dissolved salt and, moreover, to recover it with the least ossible dilution. An important feature 0 the present invention, therefore, consists in removing the lighter material from the bath and washing it with a continuous unbrokenbody of water or weak so-' lution.

The displacement of the adherent liquor 40 may be effected in an upward or downward direction but in either'case the principle is the same. The washingliquid is allowed to ascend or descend as a. continuous body in contact with the coal to be washed. The

more concentrated solution displaced thereby is removed at the same rate and in thlsway the adherent solution is removed from all articles with the least oshere should be no bro en sides of the coal sible dilution.

5 0 films or boundaries between the washing liquid and the liquid displaced thereby and as little mixing as possible should be allowed to take pace at the boundary.

The tendency of the lighter portion (the float) to rise causes the solid particles to pack in an upward direction and accordingly downward displacement of the bath liquor counteracts this tendency andthus prevents clogging. On the other hand, the tendenc .of the heavier portion (the sink) to fal to causes the solid particles to pack in a downward direction and it has now been found that this can satisfactorily be overcome by washing the sink by upward displacement of the bath liquor. If it is desired to remove 65* the bath liquor from the float by upward displacement, it will be necessary to preventthe float from being carried out of the drainer by suitable means such as a grid which will confine the solid .particles but will allow the w or hammering the vessel or by plunger action ap lied to'the contents. The beneficial effect 0 such vibration is due to the separas tion of the particles which allows liquids and possibly fine dust to pass freely betweenthem, thus assisting the draining o ration and shortening the time required. xcessive vibration shouldbe avoided since this might 00' cause diffusion of water or weak solution into the strong solution.

It is referable to remove the greater part of the ust from coal or slack prior to the flotation treatment, but this is not so essen- I tial when handling large coal or nuts. It is preferred to remove the finely divided material by passage through an air sifter or by other operations carried out on the air dry coal, but in some'cases I may treat the raw 1? when it is fed into the drainer and which might hinder the draining or washing, can be effectively removed by passing an upward current of bath liquor through t e sink prior to washing.

Calcium chloride solution may be employed as the separating liquid although other substances such as calcium nitrate can also be used. The solution should have a decidedly alkaline reaction.

Another important feature of the present invention consists in supplying the coal material to be separated below the surface of the liquid and preferably agitating the liquid at the point of introduction to facilitate disaggre ation of discrete particles of different speci c gravities.

There is a considerable advantage in re moving the greater part or as much as is practicable of the dust which, for example, passes through a screen having meshes to the linear inch.

It is particularly desirable-that not more than 2% and preferably less than 1% of such dust is present.

These data as to fineness and proportions are indicative, but I may add that the material passing a screen having 50 meshes to the linear inch consists mainly of fusain and finely divided clay and other materials.

Some of these materials are hi hly porous and others usually colloidal and have found that they considerably impede the flow of liquids between the particles which probably explains the considerable advantage obtained by removing particles of such fineness. It is therefore a particularly important feature of the invention first to remove the dust in order to facilitate the separation of all coal of low ash content from the specifically heavier mineral matter or to divide the coal itself into bright coal of very low ash content and a dull coal of higher ash content and to facilitate the draining and washing of the products. Products which may contain 2% or less of ash and are therefore of unusual tained may be returned to the bath, after having been concentrated to the requisite strength, if necessary. By this modification of my invention, draining and washing of the float and sink, by whatever method it may be carried out, will be facilitated.

In the accompanying drawings is shown a preferred form of apparatus for carrying out the invention. Fig. 1 is a diagrammatic elevation, partly in section, of an installation, and Fig. 2 is a diagrammatic elevation, partly in section, showing a modified form of the separating vessel.

In the drawing, 1 is the separating vessel which contains a solution of calcium chloride of suitable specific gravity, which, for the separation of bituminous coal into components of high ash content and low ash content, may be, for example, of specific gravity 1.35. This solution is delivered from the sup ly tank 2 through a pipe 3 having control valve 4. The coal to. be treated is contained in a hopper 5 which is situated above the vessel 1 and is delivered through the chute 6 which terminates at a point about midway between the top and bottom of the vessel 1. A driving shaft 7 extends fromthe chute, being driven from a suitable source of power through a gear 8 or other suitable drive. A screw conveyor is arranged on this shaft to feed the coal into the bath. The shaft 7 extends to the lower end of the chute and is provided with a paddle 10 to agitate the bath at the point of introduction of the coal.

The particles of coal which are of low ash content, have a lower specific gravity than the solution, and, therefore tend to float, travelling upwards forming a layer 11 which may be of pudding-like consistency, at the top of the vessel. The depth of this layer may be controlled by controlling the rate at from the top of the vessel. The bottom of the vessel 1 slopes inwardly as shown at 12, forming a hopper in which the coal of high ash13content sinks and collects as indicated at The top of the vessel 1 is surrounded by a 7 launder 14 having a sloping bottom 15. As

the top of the float rises beyond the top of the vessel as indicated at the right, the coal falls into the launder or may be mechanically removed from the top of the layer. As shown, a revolving blade 16 is mounted over the vessel and is'carried by a hub surroundin the chute 6' and provided with a worm whee 16, meshing with the worm 16 driven from a suitable source of power. This bladeis adapted to remove that portion of the layer 11 projecting beyond the top ofthe vessel 1 whence the clean coal and adherent calcium chloride falls on the slopin bottom of'the launder 15 and is delive to a shaft or tower 16. The shaft or tower is provided with a funnel shaped lower portion 17 closed by a'slide valve 18. Above the slidevalve a grid 19 is removably supported and the clean coal delivered to the tower forms a municatin column resting on this grid. When the coal is to be washed to recover the calcium chloride, water is delivered to the top of the tower through a pipe-20 having a control valve 21. An outlet pe 22 is arranged in i the bottom of the shai t or tower 16 and this opened and the valve 26 closed so that the liquid from the-bottom of the tower will enter the receptacle 24. The water is carefully superimposed on the top oftheclean coal and adherent calcium chloride, and is allowed to descend slowly as a continuous or unbroken body in contact with the coal to be washed. The calcium chloride solution from the bottom of the tower is removed to the tank 24, at the same rate of speed that the water is delivered to the top of the tower, the concentrated solution .being' thus displaced by thewater. There should be no broken films or boundaries between the washing water and the concentrated solution displace thereby and in this .Way the adherent solution is removed from all sides of the coal particles with the least ossible dilution. A relatively sharp line 0 demarcation will exist between the washing water and the concentrated solution; the water will tend .to mix with the heavier solution only to a very'shght extent. When the washing reaches the point where this weaker solution is flowing throu h the pipe 22 the vvalve 25 ma be closed and t e valve 26 opened to deliver t e less concentrated liquorto a tank 28. When water begins to flow from the bottom-of the tower, a valve 7 29 in pipe 30 is opened and the wash water run to waste. After the coal has been washed it may be removed irom the tower by opening the slide valve and displacing thegrid. The grid may be displaced by inserting a tool or instrument throu h the bottom of the tower and removing it om its support.

Instead of providing grids 19 and 34, at the bottom of the drainers, the pipes 22, 30, and 37 may be protected bg grids arranged at the side of the cones 17. urther inlet or outlet pipes suitably protected by grids may be rovided in the walls of the drainers 16 and 32 at intermediate points in the height to assist in draining, washing or drawing ofi samples for testing. a

The coal of high ash content, which may be referred to as the sink, collects at the bottom of the vessel 1 and is removed by a bucket elevator 31 to a tower 32, similar to the tower 16. The lower end of this tower is also provide with a slide valve 33 and a grid 34 to support the sink. In this tower the calcium chloride solution is removed by upward displacement.

that as little mixing as with a control valve 41.

The wash water is delivered'to the bottom of the tower through a pi cium chloride solution is removed from the top of the tower through a pipe 37 'at the same rate of speed that the water is fed so oss'ibleoccu-rs at the boundaries between t e washing water and the concentrated solution. During the upward displacement, the line of demarcation between the water and the solution is not as clear and a rather larger volume of weak solution will result. The pipe 37 is provided.

with a branch pipe 39'havmg acontrol valve 40 and beyond the branch pilpe it is provided uring the first part of the washing process when stron soution is being removed-from the'top o the tower, the valve 40is closed and the valve 41 opened so that the concentrated solution will pass through the pipe 37 to thetank 24.

35 having a control valve 36. The princip e of o ration is the.

same as in the downward disp cement ofthe adherent solution from the float. The cal-' Fi 2 shows a modified. construction 'in whic the coal is delivered from hopper 5,

through-chute 6 situated on the side of the vessel 1 by means of the screw conveyor 9. Agitation of the bath at the point of introduction is efiected by a jet of liquid suppliedthrough a tube 56 controlled by a valve 57.

The separating vessel in this case is of square or rectangular section, and the float 11' is removedby scrapers 58 mounted on a belt or band '59 which is actuated through the driving wheelsj60, The float can thus be automatically and continuously removed to the chute 15 whence it isd'elivered to the drainin tower.

he tank 24 is connected to a pum 44 by a pipe 45 having a control valve 46. e tank 28 communicates with the pipe 45 through a branch pipe 47 having a control valve 43.

The outlet side of the pump is connected to the supply tank'2 by a pipe 49 so that the strong or concentrated calcium chloride solution from the tank 24 may be returned directly to the supply tank. The pipe 49 is provided with a branch pipe '50 having a control valve 51 by means of which the weaker solution from the tank 28 may be delivered to a concentrator before it is returned to the supply tank. The strong solution may also be conveyed to the concentrator through pipe 1 if it requires concentration. The supply tank is provided with a feed pipe 52 having a control valve 53. The main receptacle 1 may be provided with an outlet pipe 54 havremoved to t etower 16 where the adherent calcium chloride solution is removed-from the coal in the manner heretofore described. 10 The solution is also recovered from the sink in the tower 32 and in practicing the process the loss of calcium chloride has been found to be les than 1% of the weight of the coal treated. This low loss renders the process.

5 commercially ractical in the se aration of coal of low as content. The a alinity of the calcium chloride solution may be maintained b adding the requisite quantity of lime to solution in theconcentrator or in m thestorage tank. r The process may be performed either 1ntermittently or continuously. When racticed continuously a number of the sha s or towers 16 are rovided and are successively connected to the bathfor charging. After one tower has been charged it is washed and drained durin which eriods other towers will be charge The liquid may be filtered at intervals to separate any fines which remain suspended by removing a portion of the liquid through the pipe 54 and conveying it to a filter. Drainage may be assisted in the towers 16 and 32 by pressure or suction and the tops of the towers may be closed after charging by suitable covers. The specific gravity of the solution of calcium chloride will vary according to the coal treated and the degree of urity desired. I have found in the case of *elsh anthracite a bath having a specific gravity of 1.4 will yield a product having no more than 2% of ash.

In washing the coal weak liquors of descending strength may first be employed to displace the strong liquor. The weak hquor may then finally be removed by water. The strong li uor, weak liquor and water may be drawn 0 separately from suitable outlets on the drainer.

The invention has been described with reference to the emplo ment of a solution of calcium chloride. Ot er substances may be employed, and I have found that forsome purposes calcium nitrate, for example is particularly suitable since solutions of higher specific gravity may be em loyed. Thus it is possible to treat the sin from the foregoing process for a further s e aration of components of different speci c gravities with a solution of higher s cific gravity. '2? The float may be likewise urther treated with the aid of a solution of lower specific avity. V The clean coal or float from the above described process is es ially suitable for the manufacture of high quahty fuel briquettes. .Ifitisrequiredtodrythefloatthismay be continuously washed and continuous lydried without interruption. 'The. ma... terial, after dryin 'by heat ma then be treated with a bin g agent and riquetted without intermediate ling.

In a further modification of the invention, the washing may be incomplete or after. wash ing predetermined quantities of the coal cal cium chloride or other catalyst, such as ferric chloride or ferrous sulphate, may be added by displacement of a portion 'of the adhering liquor with the body of a solution, colloidal so ution or suspension of the catalyst of such\ concentration that the film left on thesurso face of the particles after draining contains the catalyst in a predetermined proportion to the clean coal. I

The float may be used for the process of hy-' drogenation at high pressure, whether catalysts are added or not. v The raw material used for the flotation process is referably one in which the distribution of t e ash is such that one fraction can be separated containing the majority of the ash-forming bodies while another large fraction can be separated, which upon incineration yields very little ash. In other words, I prefer to treat the raw material in which a large fraction thereof contains a very low percentage of ash-formingv bodies. The method, however, is applicableto any carbonaceous material which is not homogeneous as regards its specific ravity but contains fragments which are 0 relatively-high average specific gravity and fragments whlch are relatively low average of specific gravity. Thus, as already stated, certain bituminous coals may be separated into a good coking portion and a feeble coking portion.

I claim:

1. In the process of separating coal into its heavier and lighter components by delivering it into a bath of calcium chloride solution having a specific gravity intermediate 0 between the specific gravities of the components to be separated so that the fragments of said heavier componentsink and the frag ments of said lighter component float, remov-, ing the floated material and removing bath liquor therefrom by displacement with a continuous unbroken body of washing liquor until a predetermined small quantity of calcium ch oride remains.

2. In the process of separating coal into its heavier and ighter components y delivering it into a bath of calcium chloride solution a continuous unbroken body of water until a 13.0

- predetermined quantity of calcium it into .a-bath of calcium chloride solution having a specific gravity intermediate between the specific gravities of the components to be separated so that the fragmentsof said to be separated so that the fragments of said' heavier component sink and the fragments of said lighter component float, the step which p it into an a ueous bath having a s heavier component sink and the fragments of lighter component float, removing from thecoal to be treated the reater part of the dust contained therein befbre delivery to the bath, removing the floated material from the bath and removing bath liquor therefrom by downward displacement with a continuous unbroken body of water until a predetermined-small quantity of calcium chloride re:

the heavier and rocess of separatin coal into its 'ghter components y delivering cific gravit interme iate between the speclfic gravities o the components to be separated so that the fra outs of said heavier component sink an the fragments of said lighter component float, removing the floated material, re-

moving-bath liquor-therefrom by dis lacement with a continuous unbroken bo y of washing liquor and displacing the last portion of the bath liquor with a solution of a substance which acts as a catalyst during subsequent combustion.

5. In the rocess of separating coal into its heavier and lighter components by delivering it into an aqueous bath having a specific gravity intermediate between the specific gravities of the components to be separated so that the fragments of said heavier component sink and the fragments of said lighter component float, remov-in from the coal to be treated the greater part o the dust contained therein before delivery to the bath, removing the floated material, removing bath liquor therefrom by displacement with a continuous unbroken body of washing liquor and displacing the last, ortion of the bath liquor with a solution of a substance which acts as a catalyst during subsequent carbonization.

6, In the process of separating coal into its heavier and lighter constituents by delivering it into a bath of calcium chloride solution having a specific gravity intermediate between the specific gravities of the components consists in employing an alkaline solution of calcium chloride.

7. In the process of separating coal into its heavier and lighter components by delivering it into a bath of aqueous solution having a specific gravity intermediate between the specific gravities of the components to be separated so that the fragments of said heavier component sink and the fragments of said li hter component'float removing at least one of said components, freeing it from. bath liquor b displacement with a continuous 'unbroken ody of washing liquid, returning at least a ortion of the displaced liquid to the bath su stantially undiluted, concentratin the remainder of sgid bath liquor recovere and returning'it to bath.

8. In'the rocess of separating coal into its heavier and 'ghter components by delivering it into a bath of aqueous solution having a specific gravity intermediate between the specific gravities of the components-to be separated so that the fragments of said heavier component sink and the fragments of said lighter component float, removing from the coal to be treated the greater part of the dust contained therein before delivery to the bath,

removing at least one of said components,

freeing it from bath liquor by displacement with a continuous unbroken body of wash- 7 ing liquid, returning at least a portion of the displaced liquid to the bathsubstantially undiluted, concentrating the remainder of said bath liquor recovered and returning it to said bath.

9. The process of separating coal into its solution having an alkaline reaction and having a specific gravity intermediate betweenthe specific gravities of the components to be separated so that the'fragments of said heavier component sink and the fragments of said lighter component float, and then removing at least one of said components, freeing it from the bath liquor by displacement with a continuous unbroken body of washing liquid, returning at least a portion of the displaced liquid to the bath substantially undiluted, concentrating the remainder of said bath liquor recovered and returning it to said bath.

11. In the process of separating coal into u its heavier and lighter components by delivering it into a bath of calcium chloride solution having a specific gravity intermediate between the specific gravities of the components to be separated so that the fragments of said heavier component sink and the frag- 10. In the process of separating coal into its heavier and lighter components by de1ivheavier and lighter components which consists in delivering it into a bath of aqueous its ments of said lighter component float, removing from'the coal to be treated the part of .the dust'contained therein be ore debody of washinfidi uid, returningat least a .leasta heavier an portion of thev aced liquid to the bath substantially undiluted, concentrating theremainder of said bath liquor recovered and returning it to said bath.-

12. The recess "of separating coal into its heavier an lighter components whic consists in delivering it into a bath of al ine calcium chloride solution having1 gravity intermediate between t so that the. fragments of said heavier component sink and the fra ents of said 1i" hter component float,-removmg at least one 0 said components, and freein it from the bath liquor b displacement with a continuous unbroken y of washin liquid, returning at rtion of the displaced liquid to. the bath su stantially "undiluted, concentratin the remainder of said bath liquor recovers and returning it to said bath.

13. The srocess of separating coal into its lighter components which consists in delivering it into a bath of alkaline calcium chloride solution having a specific gravity intermediate between the specific gravities of the components to be separated so that the fragments of said heavier compo-.

nent sinkand the fragments of said lighter component float, removing from the coal to be treated the greater part of the dust contained therein before delivery to the bath and removin at least one-of said com onents, freeingit from the bath-liquor by is lacement with a continuous unbroken bosy of washin liquid, returning at least a portion of the displaced liquid to the bath substantially undiluted, concentrating the remaina specific e specific ,gravities of the components to be separated body of washinfilli ;n nor as a said' a is 1a; m of coal'inte its heavleran fighter components which consists m delivering it into abath of aqueous solution having a gravity intermediate between the specific gravities of the components to be separatedso that the fragments of said heavier com nent sink and the fragments of saidligter com nient float, b introducing it below the sur ace of the bat ,then removin at least one of said com onents, freeing it m the bath liquor by isplacementwith a continuous unbroken uid, returning at least a seed liquid to the bath the and portion of the v 's substantially .undi uted, concentratin' remainder of said bath liquor recove returning it to said bath.

16. In the process of separating coal into ts heavier and lighter components by delivenng it into a ath of calcium chloride solution having'aspecific gravity intermediate between the specific gravities of the components to be separated so that the fragments of said heavier component sink and the fragments of said lighter component float, removing from the coal to be treated the greator art of the dust contained therein before dellvery to the bath, continuously removing,

filterin and returning to the bath a portion of the iquor in order to avoidaccumulation of fine material in the bath, removin at least one of said com onents, freeing it roin the bath liquor by is lacement with a continuous-unbroken bo y of washing li uid, returning at least a portion of the isplaced liquid to the bath substantially undiluted,

concentrating the remainder of said bath li uor recovered and returning it to said bath. n testimony whereof I aflix my si ature,

RUDOLF LES ING.

der of said bath liquorrecovered and returning it to said bath.

14. The process of separating coal into its heavier and lighter components which con- 4 sists in delivering it into a separating bath of calcium chloride solution having a specific gravity intermediate between the specific gravities of the components to be separated so that the fragments of said heavier component sink and the fragments of said lighter component float, removing at least one of said components and freeing it from the bath liquor by displacement with a continuous unbroken body of washing liquid, returning at least a portion of the displaced liquid to the bath substantially undiluted,

concentrating the remainder of said bath liquor recovered with the addition of a material givingan alkaline reaction to maintain therequired alkalinity and returning 

